332 research outputs found

    The Legal Regime Governing the Recovery of Underwater Cultural Resources in the United States

    Get PDF
    Historic wrecks exist in many of the navigable waters of the United States, particularly along the Atlantic and Gulf coasts. Attention will mainly focus, however, on the waters off Florida. These often dangerous waters, as part of a long-established trade route, contain more than their share of historic wrecks. As a number of these are Spanish galleons, wrecked on their way to Europe with value cargoes of gold, silver and precious stones, claim to such sites has been the subject of bitter disputes. The results of the legal battles arising from these disputes will have profound implications for the future of underwater antiquities, not only in Florida, but throughout the navigable waters of the United States

    Theoretical and Software Considerations for General Dynamic Analysis Using Multilevel Substructured Models

    Get PDF
    An approach is presented for the dynamic analysis of complex structure sy~t'=!!!S using the finite element method and multilevel substructured models. The fixedinterface method is selected for substructure reduction because of its efficiency, accurac and adaptability to restart and reanalysis. This method is extended to reduction of substructures which are themselves composed of reduced substructures. Emphasis is placed on the implementation and performance of the method in a general purpose software system. Solution algorithms consistent with the chosen data structures are presented in detail. This study demonstrates that successful finite element software requires the use of software executives to supplement the algorithmic language. As modeling and analysis techniques become more complex, proportionally more implementation effort is spent on data and computer resource management. Executive systems are essential tools for these tasks. The complexity of the implementation of restart and reanalysis porcedures also illustrate the need for executive systems to support the non computational aspects of the software. The example problems show that significant computational efficiencies can be achieved through proper use of substructuring and reduction techniques without sacrificing solution accuracy. The unique restart and reanalysis capabilities developed in this study and the flexible procedures for multilevel substructured modeling allow analysts to achieve economical yet accurate analyses of complex structural systems

    Spacecraft applications of advanced global positioning system technology

    Get PDF
    The purpose of this study was to evaluate potential uses of Global Positioning System (GPS) in spacecraft applications in the following areas: attitude control and tracking; structural control; traffic control; and time base definition (synchronization). Each of these functions are addressed. Also addressed are the hardware related issues concerning the application of GPS technology and comparisons are provided with alternative instrumentation methods for specific functions required for an advanced low earth orbit spacecraft

    Towards rigorously faking bidirectional model transformations

    Get PDF
    Bidirectional model transformations (bx) are mechanisms for auto-matically restoring consistency between multiple concurrently modified models. They are, however, challenging to implement; many model transformation languages not supporting them at all. In this paper, we propose an approach for automatically obtaining the consistency guarantees of bx without the complexities of a bx language. First, we show how to “fake” true bidirectionality using pairs of unidirectional transformations and inter-model consistency constraints in Epsilon. Then, we propose to automatically verify that these transformations are consistency preserving — thus indistinguishable from true bx — by defining translations to graph rewrite rules and nested conditions, and leveraging recent proof calculi for graph transformation verification

    Evaluating time-lapse borehole gravity for CO2 plume detection at SECARB Cranfield

    Get PDF
    Bureau of Economic Geolog

    High-speed Civil Transport Aircraft Emissions

    Get PDF
    Estimates are given for the emissions from a proposed high speed civil transport (HSCT). This advanced technology supersonic aircraft would fly in the lower stratosphere at a speed of roughly Mach 1.6 to 3.2 (470 to 950 m/sec or 920 to 1850 knots). Because it would fly in the stratosphere at an altitude in the range of 15 to 23 km commensurate with its design speed, its exhaust effluents could perturb the chemical balance in the upper atmosphere. The first step in determining the nature and magnitude of any chemical changes in the atmosphere resulting from these proposed aircraft is to identify and quantify the chemically important species they emit. Relevant earlier work is summarized, dating back to the Climatic Impact Assessment Program of the early 1970s and current propulsion research efforts. Estimates are provided of the chemical composition of an HSCT's exhaust, and these emission indices are presented. Other aircraft emissions that are not due to combustion processes are also summarized; these emissions are found to be much smaller than the exhaust emissions. Future advances in propulsion technology, in experimental measurement techniques, and in understanding upper atmospheric chemistry may affect these estimates of the amounts of trace exhaust species or their relative importance

    Systematic reviews: guidance relevant for studies of older people

    Get PDF
    Systematic reviews and meta-analyses are increasingly common. This article aims to provide guidance for people conducting systematic reviews relevant to the healthcare of older people. An awareness of these issues will also help people reading systematic reviews to determine whether the results will influence their clinical practice. It is essential that systematic reviews are performed by a team which includes the required technical and clinical expertise. Those performing reviews for the first time should ensure they have appropriate training and support. They must be planned and performed in a transparent and methodologically robust way: guidelines are available. The protocol should be written—and if possible published—before starting the review. Geriatricians will be interested in a table of baseline characteristics, which will help to determine if the studied samples or populations are similar to their patients. Reviews of studies of older people should consider how they will manage issues such as different age cut-offs; non-specific presentations; multiple predictors and outcomes; potential biases and confounders. Systematic reviews and meta-analyses may provide evidence to improve older people's care, or determine where new evidence is required. Newer methodologies, such as meta-analyses of individual level data, network meta-analyses and umbrella reviews, and realist synthesis, may improve the reliability and clinical utility of systematic reviews

    Statutory frameworks, institutions and policy processes for climate adaptation : Final Report

    Get PDF
    Funded under the National Climate Change Adaptation Research Facility, this study addresses two objectives: To assess the extent to which existing statutory frameworks, associated institutions and policy processes support or impede national adaptation planning and practice, and To make a significant contribution to the development and implementation of a strategic national policy framework. The rationale for conducting this study was two-fold. First, that significant climate change is unavoidable and that it is in Australia’s national interest to adapt to those changes. Climate impacts are many and varied, direct and indirect, hard to predict and quantify generally but particularly at the local scale, and impacts will inevitably affect all sectors and jurisdictions. For this reason, it is a complex policy problem. The IPCC, for example, identifies ten key areas of impact for Australia including increasing frequency and intensity of extreme events such as droughts, bushfires and floods, higher peak temperatures for longer periods of time, and sea level rise. Despite the lack of hard economic data with respect to costs and benefits that might underpin formal business cases to determine precise levels of investment needed for adaptation, the case to adapt is compelling considering the projected effects to Australia’s economy, infrastructure, communities, environment and human life. Second, Australia’s capacity to adapt to climate change will rely on robust, efficient, transparent, fair and flexible institutions which build a resilient and enabling environment in which the necessary behavioural change can occur. While humans and our institutions have a remarkable capacity to adapt to all manner of change, this can occur at great cost to society as a whole or certain segments of it without the guiding hand of judicious policy intervention. This report synthesises our key findings against the two project objectives. In doing so, it focuses on (i) where institutional arrangements currently support or impede climate adaptation policy, and (ii) where revisions or new institutions may be required, and the potential for a strategic national policy framework to achieve those reforms
    corecore